What material is typically used for fire-rated cable jackets in plenum spaces?

The correct choice for the material typically used for fire-rated cable jackets in plenum spaces is fluorinated ethylene polymer (FEP). FEP is designed to withstand high temperatures and has excellent flame resistance, making it suitable for use in environments where fire safety is a critical concern, such as plenum spaces, which are areas used for air circulation in heating and air conditioning systems.

In these spaces, the cables must not only resist the spread of fire but also minimize the release of toxic fumes and smoke in case of a fire. FEP meets these stringent requirements due to its high thermal stability and low smoke emission properties, ensuring safety in commercial and residential buildings.

Other options like polyvinyl chloride (PVC) and low-smoke PVC may not offer the same level of temperature resistance or low toxicity in combustion that FEP provides, while standard rubber insulation is not typically used for fire-rated applications due to its vulnerability to flames and lack of specific fire resistance features required for plenum installations.